Positional tracking assisted beam forming in wireless virtual reality systems

ABSTRACT

Embodiments of the present disclosure support a head-mounted display (HMD) wirelessly coupled to a console. The HMD includes a positional tracking system, a beam controller and a transceiver. The positional tracking system tracks position of the HMD and generates positional information describing the tracked position of the HMD. The transceiver communicates with a console via a wireless channel, in accordance with communication instructions, the communication instructions causing the transceiver to communicate over one directional beam of a plurality of directional beams. The beam controller determines a change in the positional information. Based on the change to the positional information, the beam controller determines a directional beam of the plurality of directional beams. The beam controller further generates the communication instructions identifying the determined directional beam, and provides the communication instructions to the transceiver.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of pending U.S. application Ser. No.15/433,817, filed Feb. 15, 2017, which is incorporated by reference inits entirety.

BACKGROUND

The present disclosure generally relates to virtual and augmentedreality systems, and specifically relates to positional trackingassisted beam forming in wireless virtual reality and augmented realitysystems.

It is desirable to establish a reliable and fast wireless communicationbetween a console and a head-mounted display (HMD) in a virtual reality(VR) system, an augmented reality (AR) system, a mixed reality (MR)system, or some combination thereof, to, e.g., “cut the cord” betweenthe console and the HMD. A wireless communication based on extremelyhigh carrier frequencies, such as communication based on 60 GHz carrierfrequency in accordance with the IEEE 802.11ad standard or the IEEE802.11ay standard represents a promising technology for achievingreliable wireless experience in VR, AR and MR systems. A base station(e.g., console) that wirelessly communicates with a client (e.g., HMD)based on 60 GHz carrier frequency employs beam forming to compensate fora path loss and maintain a quality of wireless link above apredetermined threshold value. The base station typically employs thebeam forming based on beam training and beam tracking in order to ensureits effectiveness.

In the IEEE 802.11ad standard, the beam training and beam tracking isperformed by employing a sector level sweep and a beam refinementprotocol. However, the beam training and beam tracking causes a highoverhead and large latency. The high overhead of the beam training andbeam tracking is due to a feedback communicated between a pair ofwireless devices (e.g., the console and the HMD), which consumes anadditional communication bandwidth. The large latency of the beamtraining and beam tracking is due to a latency of the sector level sweepthat can be approximately between 2 ms and 100 ms. Thus, the beamforming based on sector level sweep cannot handle typical movements ofthe HMD as the beam forming based on sector level sweep can support theHMD's movement speeds of only up to a certain speed that is slower thana speed of the typical HMD's movements. A latency of the beam refinementprotocol is lower and approximately 200 μs-300 μs per iteration.However, the beam refinement protocol typically needs multipleiterations to determine a preferred directional beam for communicationbetween a pair of wireless devices. If only considering the latency, thebeam refinement protocol can support typical movement speeds of the HMD.However, the beam refinement protocol is often subject to manyimperfections and may result in data losses. Furthermore, the accuracyof beam training and beam tracking is limited by the digital basebandestimate variation and antenna beam pattern. Because of that, a HMD maynot be able to use an optimal beam direction for wireless communicationwith a console. This may also cause delay between beam switchingprocesses. In addition, the beam training and beam tracking featuresnon-awareness in relation to non-line-of-sight (NLOS) conditions betweena pair of wireless devices. In the case NLOS condition is presentbetween the pair of wireless devices, communication based on the beamtraining and beam tracking cannot provide prompt remedy, which causesloss of data when communicated between the wireless devices.

SUMMARY

Embodiments of the present disclosure support a head-mounted display(HMD) that wirelessly communicates with a console. The HMD and theconsole may be part of, e.g., a wireless virtual reality (VR) system, awireless augmented reality (AR) system, a wireless mixed reality (MR)system, or some combination thereof. The HMD includes a positionaltracking system, a transceiver, and a beam controller. The positionaltracking system is configured to track a position of the HMD andgenerate positional information describing the tracked position of theHMD. The transceiver is configured to communicate with a console via awireless channel, in accordance with communication instructions, thecommunication instructions causing the transceiver to communicate overone directional beam of a plurality of directional beams. In someembodiments, some or all of the directional beams used by thetransceiver of the HMD for wireless communication with the console canbe directional narrow beams. In alternate embodiments, some or all ofthe directional beams used by the transceiver of the HMD for wirelesscommunication with the console can be directional wide beams. The beamcontroller is configured to determine a change in the positionalinformation. Based in part on the change to the positional information,the beam controller determines a directional beam of the plurality ofdirectional beams. The beam controller further generates thecommunication instructions identifying the determined directional beam,and provides the communication instructions to the transceiver.

The console that wirelessly communicates with the HMD includes apositional tracking system, a beam controller, and a transceiver. Thepositional tracking system of the console tracks a position of the HMDand generates positional information describing the tracked position ofthe HMD. The beam controller of the console determines a change in thepositional information. Based in part on the change to the positionalinformation, the beam controller determines a directional beam of aplurality of directional beams of the HMD. The beam controller of theconsole further generates communication instructions identifying thedetermined directional beam. The transceiver of the console communicateswith the HMD via a wireless channel, and transmits the communicationinstructions to the HMD, the communication instructions causing the HMDto communicate with the apparatus over the determined directional beam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram of a head-mounted display (HMD), in accordance withan embodiment.

FIG. 1B is a cross section of a front rigid body of the HMD in FIG. 1A,in accordance with an embodiment.

FIG. 2A is a wireless system that includes the HMD in FIG. 1A in a firstposition wirelessly communicating with a console, in accordance with anembodiment.

FIG. 2B is the wireless system shown in FIG. 2A where the HMD switches abeam for wireless communication with the console to a preferreddirection when the HMD moves relative to the console from the firstposition to a second position, in accordance with an embodiment.

FIG. 2C is the wireless system shown in FIG. 2A where the HMD switches abeam for wireless communication with the console to a preferreddirection when the HMD moves relative to the console from the secondposition to a third position, in accordance with an embodiment.

FIG. 3 is an example of beam training applied at the HMD in FIG. 1A usedfor beam switching when the HMD wirelessly communicates with a console,in accordance with an embodiment.

FIG. 4 is an example of an inside-out positional tracking applied at theHMD in FIG. 1A for beam switching when the HMD wirelessly communicateswith a console, in accordance with an embodiment.

FIG. 5A is a wireless system that includes the HMD in FIG. 1A wirelesslycommunicating with a console, in accordance with an embodiment.

FIG. 5B is the wireless system shown in FIG. 5A where the console usesan outside-in positional tracking to switch its directional beam forwireless communication with the HMD when the HMD moves relative to theconsole, in accordance with an embodiment.

FIG. 5C is the wireless system shown in FIG. 5A where the consolemaintains a directional beam for wireless communication with the HMDalthough the HMD changed position relative to the console, in accordancewith an embodiment.

FIG. 6 is a wireless system that includes the HMD in FIG. 1A wirelesslycommunicating with a console, wherein the console sets up a radiofrequency (RF) zone where a quality of wireless communication betweenthe HMD and the console is above a threshold level, in accordance withan embodiment.

FIG. 7 is a flow chart illustrating a process of positional trackingassisted beam forming, which may be implemented at the HMD shown in FIG.1A, in accordance with an embodiment.

FIG. 8 is a flow chart illustrating a process of positional trackingassisted beam forming, which may be implemented at a console wirelesslycommunicating with the HMD shown in FIG. 1A, in accordance with anembodiment.

FIG. 9 is a block diagram of a system environment that includes the HMDshown in FIG. 1A wirelessly communicating with a console, in accordancewith an embodiment.

The figures depict embodiments of the present disclosure for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles, or benefits touted, of the disclosure described herein.

DETAILED DESCRIPTION

Disclosed embodiments support a head-mounted display (HMD) that iswirelessly coupled to a console. The HMD and the console may be part of,e.g., a wireless virtual reality (VR) system, a wireless augmentedreality (AR) system, a wireless mixed reality (MR) system, or somecombination thereof. Embodiments disclosed herein support the HMD thatcommunicates wirelessly with the console using a narrow beam that isoriented in a particular direction, which is herein referred to as adirectional narrow beam. However, in alternate embodiments, the HMD canutilize a wide beam oriented in a particular direction to wirelesslycommunicate with the console, which is herein referred to as adirectional wide beam. The console communicates wirelessly with the HMDusing a directional wide beam or a directional narrow beam. Adirectional narrow beam focuses a transmission signal to a directiondirectly pointing to a receiving device, and may occupy a region ofspace having a beam diameter below a threshold value. A directional widebeam provides transmission of a signal in a direction that may notdirectly point to a receiving device, and may occupy a region of spacehaving a beam diameter above the threshold value. In some systems, theHMD uses an “inside-out” positional tracking while wirelesslycommunicating with the console to determine location of the HMD relativeto the console. When the HMD determines that its location changedrelative to the console, the HMD can automatically redirect the narrowbeam to another direction to ensure a quality of wireless link betweenthe HMD and the console is above a threshold value. In some embodiments,where the line-of-sight (LOS) is lost between the console and the HMD,the HMD may automatically redirect a transmission beam to a reflectionpath. In alternate embodiments, a console wirelessly communicating witha HMD can apply an “outside-in” positional tracking to determine aposition of the HMD relative to the console. In these cases, the consolecan instruct the HMD in what direction to adjust the narrow beam toensure the link quality is above the threshold value, based on thedetermined position of the HMD.

FIG. 1A is a diagram of a HMD 100, in accordance with an embodiment. TheHMD 100 may be part of, e.g., a VR system, an AR system, a MR system, orsome combination thereof. In embodiments that describe AR system and/ora MR system, portions of a front side 102 of the HMD 100 are at leastpartially transparent in the visible band (˜380 nm to 750 nm), andportions of the HMD 100 that are between the front side 102 of the HMD100 and an eye of the user are at least partially transparent (e.g., apartially transparent electronic display). The HMD 100 includes a frontrigid body 105, a band 110, a reference point 115, and an antenna array120. In some embodiments, the antenna array 120 integrated into thefront rigid body 105 comprises multiple phased-array antennas, which maybe used for wireless communication with a console (not shown in FIG. 1A)based on beam forming. The HMD 100 performs wireless communication withthe console in different beam directions using the phased-array antennasof the antenna array 120. The antenna array 120 can change a beamdirection for wireless communication by applying specific beam formingcoefficients.

In some embodiments, the HMD 100 shown in FIG. 1A also includes a depthcamera assembly (DCA) configured to determine depth information of alocal area surrounding some or all of the HMD 100. In these embodiments,the HMD 100 would also include an imaging aperture 125 and anillumination aperture 130, and an illumination source of the DCA wouldemit light (e.g., structured light) through the illumination aperture130. An imaging device of the DCA would capture light from theillumination source that is reflected/scattered from the local areathrough the imaging aperture 125. In some embodiments, the HMD 100 shownin FIG. 1A also includes one or more locators 135. The locators 135 areobjects located in specific positions on the HMD 100 relative to oneanother and relative to the reference point 115. A locator 135 may be alight emitting diode (LED), a corner cube reflector, a reflectivemarker, a type of light source that contrasts with an environment inwhich the HMD 100 operates, or some combination thereof.

In one embodiment, the front rigid body 105 includes one or moreelectronic display elements (not shown in FIG. 1A), one or moreintegrated eye tracking systems (not shown in FIG. 1A), an InertialMeasurement Unit (IMU) 140, one or more position sensors 145, and thereference point 115. In the embodiment shown by FIG. 1A, the positionsensors 145 are located within the IMU 140, and neither the IMU 140 northe position sensors 145 are visible to a user of the HMD 100. The IMU140 is an electronic device that generates fast calibration data basedon measurement signals received from one or more of the position sensors145. A position sensor 145 generates one or more measurement signals inresponse to motion of the HMD 100. Examples of position sensors 145include: one or more accelerometers, one or more gyroscopes, one or moremagnetometers, another suitable type of sensor that detects motion, atype of sensor used for error correction of the IMU 140, or somecombination thereof. The position sensors 145 may be located external tothe IMU 140, internal to the IMU 140, or some combination thereof.

In some embodiments, the HMD 100 utilizes measurement data obtained fromat least one of the DCA, the locators 135, the IMU 140 and the positionsensors 145 to determine and track a position and/or orientation of theHMD 100 relative to a specific reference point on the console thatwirelessly communicates with the HMD 100. The HMD 100 may include one ormore processors (not shown in FIG. 1A) configured to translate thedetermined and tracked relative position of the HMD 100 into informationabout a preferred direction for a transmission beam for wirelesscommunication with the console. In one or more embodiments, the antennaarray 120 may use the transmission beam with the preferred direction tocommunicate over a wireless link with the console, wherein a quality ofthe wireless link is above a predetermined threshold level.

FIG. 1B is an example cross section 150 of the front rigid body 105 ofthe embodiment of the HMD 100 shown in FIG. 1A. As shown in FIG. 1B, thefront rigid body 105 includes an electronic display 155 and an opticalassembly 160 that together provide image light to an exit pupil 165. Theexit pupil 165 is the location of the front rigid body 105 where auser's eye 170 is positioned. For purposes of illustration, FIG. 1Bshows a cross section 150 associated with a single eye 170, but anotheroptical assembly 160, separate from the optical assembly 160, providesaltered image light to another eye of the user.

The electronic display 155 generates image light. In some embodiments,the electronic display 155 includes an optical element that adjusts thefocus of the generated image light. The electronic display 155 displaysimages to the user in accordance with data received from a console (notshown in FIG. 1B). In various embodiments, the electronic display 155may comprise a single electronic display or multiple electronic displays(e.g., a display for each eye of a user). Examples of the electronicdisplay 155 include: a liquid crystal display (LCD), an organic lightemitting diode (OLED) display, an inorganic light emitting diode (ILED)display, an active-matrix organic light-emitting diode (AMOLED) display,a transparent organic light emitting diode (TOLED) display, some otherdisplay, a projector, or some combination thereof. The electronicdisplay 155 may also include an aperture, a Fresnel lens, a convex lens,a concave lens, a diffractive element, a waveguide, a filter, apolarizer, a diffuser, a fiber taper, a reflective surface, a polarizingreflective surface, or any other suitable optical element that affectsthe image light emitted from the electronic display. In someembodiments, one or more of the display block optical elements may haveone or more coatings, such as anti-reflective coatings.

The optical assembly 160 magnifies received light from the electronicdisplay 155, corrects optical aberrations associated with the imagelight, and the corrected image light is presented to a user of the HMD100. At least one optical element of the optical assembly 160 may be anaperture, a Fresnel lens, a refractive lens, a reflective surface, adiffractive element, a waveguide, a filter, a reflective surface, apolarizing reflective surface, or any other suitable optical elementthat affects the image light emitted from the electronic display 155.Moreover, the optical assembly 160 may include combinations of differentoptical elements. In some embodiments, one or more of the opticalelements in the optical assembly 160 may have one or more coatings, suchas anti-reflective coatings, dichroic coatings, etc. Magnification ofthe image light by the optical assembly 160 allows elements of theelectronic display 155 to be physically smaller, weigh less, and consumeless power than larger displays. Additionally, magnification mayincrease a field of view of the displayed media. For example, the fieldof view of the displayed media is such that the displayed media ispresented using almost all (e.g., 110 degrees diagonal), and in somecases all, of the user's field of view. In some embodiments, the opticalassembly 160 is designed so its effective focal length is larger thanthe spacing to the electronic display 155, which magnifies the imagelight projected by the electronic display 155. Additionally, in someembodiments, the amount of magnification may be adjusted by adding orremoving optical elements.

In some embodiments, the front rigid body 105 further includes a DCA 175for determining depth information of one or more objects (e.g., walls,furniture, console, etc.) in a local area 180 surrounding some or all ofthe HMD 100. The determination of depth information can be also referredto herein as depth mapping or three-dimensional (3D) reconstruction ofthe local area 180. The DCA 175 may include an illumination source 185,an imaging device (camera) 190, and a controller 195 that may be coupledto both the illumination source 185 and the imaging device 190. Theillumination source 185 emits light (e.g., structured light) through theillumination aperture 130. The illumination source 185 may be composedof a plurality of laser-type light emitters on a single substrateconfigured to simultaneously or in different time instants (e.g.,controlled by the controller 195) emit a plurality of light beams, e.g.,in the form of a structured light pattern. The imaging device 190captures light from the illumination source 185 that isreflected/scattered from the local area 180 through the imaging aperture125. The controller 195 may be configured to determine depth informationof the one or more objects in the local area 180 based on the capturedreflected/scattered light. In some embodiments, in addition to shapes ofthe objects, the controller 195 can be configured to determine materialsof which the objects are composed, such as metal, glass, wood, carpet,etc.

FIG. 2A illustrates a wireless system 200 that includes a HMD 210 in afirst position wirelessly communicating with a console 220, inaccordance with an embodiment. The wireless system 200 is a wireless VRsystem, a wireless AR system, a wireless MR system, or some combinationthereof. The HMD 210 is an embodiment of the HMD 100 shown in FIG. 1A.As shown in FIG. 2A, the console 220 uses at least one directional widebeam 225 (i.e., tapering) to alleviate the requirement for beam trackingat the console 220. In an alternate embodiment (not shown in FIG. 2A),the console 220 may use a directional narrow beam when wirelesslycommunicating with the HMD 210. The HMD 210 uses a directional narrowbeam (e.g., a first directional narrow beam 230 shown in FIG. 2A) tomaintain link gain when wirelessly communicating with the console 220.Alternatively, the HMD 210 may use a directional wide beam to wirelesslycommunicate with the console 220.

FIG. 2B illustrates the wireless system 200 where the HMD 210 switches anarrow beam for wireless communication with the console 220 to apreferred direction when the HMD 210 moves from the first position to asecond position relative to a specific reference point on the console220 (not shown in FIG. 2B). The HMD 210 may apply an “inside-out”positional tracking to switch wireless communication with the console220 from the first directional narrow beam 230 to a second directionalnarrow beam 235. An “inside-out” positional tracking applied at a HMDrelates to continuous tracking of position/orientation of the HMDrelative to a console, and to automatic beam switching at the HMD basedon a detected change in HMD's position/orientation without any feedbackfrom the console. During the “inside-out” positional tracking, the HMD210 tracks its position relative to the reference point on the console220. Because the HMD 210 knows its location relative to the referencepoint on the console 220, the HMD 210 can determine its movementrelative to the console 220. Then, the HMD 210 can automaticallyredirect a narrow beam to a new direction for communicating with theconsole 220, i.e., the HMD 210 switches wireless communication with theconsole 220 from the first directional narrow beam 230 to a seconddirectional narrow beam 235 as shown in FIG. 2B. By switching thedirectional beams, the HMD 210 ensures that a quality of communicationlink between the HMD 210 and the console 220 is still above apredetermined threshold value.

FIG. 2C illustrates the wireless system 200 where the HMD 210 switches anarrow beam for wireless communication with the console 220 to a newpreferred direction when the HMD 210 moves relative to the console 220from the second position to a third position, in accordance with anembodiment. As shown in FIG. 2C, when the HMD 210 further moves relativeto the specific reference point on the console 220, the HMD 210 isconfigured to switch wireless communication with the console 220 fromthe second directional narrow beam 235 to a third directional narrowbeam 240, again to ensure that a quality of communication link betweenthe HMD 210 and the console 220 is still above a predetermined thresholdvalue. Note that no feedback is transmitted from the console 220 to theHMD 210 or from the HMD 210 to the console 220 with any informationabout quality of links associated with different directional beams.Thus, communication bandwidth overhead is reduced by employing the“inside out” positional tracking. In one embodiment, the console 220emits a beacon signal (e.g., visible beacon) via an antenna mounted onthe console 220 (not shown in FIGS. 2A-2C). The HMD 210 receives thebeacon signal and tracks its position/orientation relative to theconsole 220 using the beacon signal. In this setup, the HMD 210 maytrack its position/orientation relative to the console 220 faster andmore accurately in comparison with a setup when no beacon signal isemitted from the console 220.

FIG. 3 is an example 300 of beam training applied at a HMD (e.g., theHMD 100 in FIG. 1A) used for beam switching when the HMD wirelesslycommunicates with a console, in accordance with an embodiment. Packetsof data may be wirelessly communicated between the HMD and the console,e.g., from the HMD to the console. For example, the HMD transmits a datapacket 305 to the console using a first directional narrow beam of aplurality of directional narrow beams of the HMD. As shown in FIG. 3,during transmission of the data packet 305, a user of the HMD may moverelative to a specific reference point on the console. Before switchinga directional narrow beam for communication with the console, the HMDmay perform beam training in order to determine a preferred directionalnarrow beam for wireless communication with the console.

In some embodiments, the HMD performs beam training by employing beamlevel sweep during a beam training period 310 when the HMD transmitspackets 315 ₁, 315 ₂, . . . , 315 _(N) to the console using variousdirectional narrow beams. The console receives the packets 315 ₁, 315 ₂,. . . , 315 _(N) transmitted using different directional narrow beamsand sends a feedback to the HMD indicating to the HMD a preferreddirectional narrow beam that provides a best link quality among thedifferent directional narrow beams. The beam training period 310 willlast a certain period of time, during which the communicationperformance may drop, e.g., due to the usage of an outdated directionalbeam for communications between the HMD and the console.

At the end of the beam training period 310, the beam training iscompleted and the HMD is able to determine a new preferred directionalnarrow beam for communication with the console, which ensures that aquality of communication link between the HMD and the console is finallyabove a predetermined threshold value. At this point, after the entirebeam period 310, the HMD switches packet transmission from the firstdirectional narrow beam to the new preferred directional narrow beam,and the HMD transmits the data packet 320 using the new preferreddirectional narrow beam. In addition to the degraded link quality duringthe beam training period 310, a latency of switching directional narrowbeams at the HMD may be prohibitively long and depends on duration ofthe beam training period 310, which may be up to between 100 ms and 200ms. The latency of beam switching based on beam training often cannotsupport quick movements of the user wearing the HMD.

FIG. 4 is an example 400 of an “inside-out” positional tracking appliedat a HMD (e.g., the HMD 100 in FIG. 1A, the HMD 210 in FIGS. 2A-2C),which may be used for beam switching when the HMD wirelesslycommunicates with a console (e.g., the console 220 in FIGS. 2A-2C), inaccordance with an embodiment. A positional tracking system of the HMDapplies an “inside-out” positional tracking 410 to track aposition/orientation of the HMD relative to a specific reference pointon the console. In some embodiments, the positional tracking system maycomprise one or more processors coupled to at least one of the DCA, oneor more locators, an IMU, and one or more position sensors of the HMDfor determining and tracking location of the HMD relative to thereference point on the console. As the HMD moves (e.g., movement causedby a user of the HMD) during transmission of a packet 415, the HMDapplies the positional tracking 410 to detect a change inposition/orientation of the HMD relative to the console. The positionaltracking system of the HMD tracks over time positions/orientations ofthe HMD and periodically updates information about itsposition/orientation relative to the console. Based on the trackedpositions/orientations of the HMD over a defined time period, the HMDdetects the change in its position/orientation relative to the console.As a new position of the HMD is detected, a conversion unit of a beamcontroller in the HMD may perform a position translation 420 totranslate positional information determined by the positional tracking410 into a beam pointing direction that corresponds to one specificdirectional narrow beam of the HMD. The positional information of theHMD may comprise various informations related to position/orientation ofthe HMD relative to the reference point on the console. For example, thepositional information may comprise information about an angularposition of the HMD relative to the reference point on the console,information about a rotational position of the HMD relative to thereference point, information about a 3D coordinate position of the HMD(e.g., 3D coordinate position of a reference point on the HMD) relativeto the reference point on the console, etc. As the HMD knows itsposition/orientation relative to the reference point on the console, theconversion unit of the beam controller of the HMD may select onedirectional narrow beam of a plurality of directional narrow beams ofthe HMD, wherein the selected directional narrow beam covers a preferredregion in space comprising the reference point. In an embodiment, theHMD may perform the positional tracking 410 and the position translation420 during transmission of the packet 415.

In some embodiments, information about the beam pointing direction (theselected preferred directional narrow beam) is passed directly to amodem of the HMD, i.e., to a media access control (MAC) layer/firmwareblock 430, which may be also part of the beam controller in the HMD. TheHMD's modem (i.e., the MAC layer/firmware block 430) is configured toswitch a directional narrow beam of the HMD to a narrow beam with aproper direction when a user of the HMD moved relative to the referencepoint on the console. A radio frequency (RF) beam selection block 440 iscoupled to a transceiver of the HMD, and the RF beam selection block 440is configured to perform switching to a new preferred directional narrowbeam. The RF beam selection block 440 instructs the transceiver of theHMD to send data to the console using the new preferred directionalnarrow beam instead of previously used directional narrow beam. Thus,the transceiver of the HMD may transmit a packet 445 that immediatelyfollows the packet 415 using the new preferred directional narrow beam.Note that the latency of beam switching based on the “inside-out”positional tracking is reduced by duration of the beam training period310 in FIG. 3 in comparison with the beam switching based on the beamtraining.

In some embodiments, as the user of the HMD moves and LOS still existsbetween the HMD and the console, the HMD is configured to switchwireless communication with the console to a newly determineddirectional narrow beam such that to maintain LOS without delay. If itis previously determined that non-line-of-sight (NLOS) condition isestablished between the HMD and the console as the HMD knows itspositional information relative to the console, the HMD is configured toswitch to a preferred reflection path directly without delay. In anembodiment, the HMD may perform a background RF beam training with verysmall overhead. In alternate embodiments, if the console can afford toperform extra beam tracking by itself, the console can use a relativelynarrow directional beam for wireless communication with the HMD, insteadof a wide directional beam, e.g., the wide directional beam 225 shown inFIGS. 2A-2C.

In addition to a short latency of beam switching, the “inside-out”positional tracking illustrated in FIG. 4 features no additionalcommunication bandwidth overhead, as no feedback is transmitted from theconsole 220 to the HMD 210 or vice versa as in the case of beamswitching based on the beam training shown in FIG. 3. Furthermore, the“inside-out” positional tracking is accurate as the HMD has knowledge ofits position/orientation relative to the console. The “inside-out”positional tracking also avoids side-lobe issues when the HMDcommunicates with the console via a narrow directional beam. Whenapplying the “inside-out” positional tracking, the HMD identifies NLOSimmediately without any error. In some embodiments, a latency involvedin the “inside-out” positional tracking procedure illustrated in FIG. 4that includes the positional tracking 410, the position translation 420,beam switching using the MAC layer/firmware 430 and the RF beamselection block 440 may be up to several milliseconds, which may besuitable for typical movements of the HMD's user.

FIG. 5A illustrates a wireless system 500 that includes a HMD 510wirelessly communicating with a console 520, in accordance with anembodiment. The wireless system 500 is a wireless VR system, a wirelessAR system, a wireless MR system, or some combination thereof. The HMD510 is an embodiment of the HMD 100 shown in FIG. 1A. In someembodiments, the console 520 uses an “outside-in” positional trackingfor beam switching. An “outside-in” positional tracking relates tocontinuous determination and tracking of position/orientation of a HMDrelative to a reference point on the console, sending feedbackinformation to the HMD about a change in position/orientation of theHMD, and to automatic beam switching performed at the HMD based on thefeedback information received from the console. In addition, based onthe positional information about the HMD determined at the console, theconsole may switch its directional beam to another directional beam forwireless communication with the HMD.

In the setup shown in FIG. 5A, the console 520 may comprise a camera,one or more locators, an IMU and/or one or more positional sensors (notshown in FIG. 5A) for determining and tracking the position/orientationof the HMD 510 relative to the reference point on the console 520. In analternate configuration, the console 520 may utilize measurements from aDCA, one or more locators, an IMU and/or one or more positional sensorsof the HMD 510 (not shown in FIG. 5A) for determining and tracking theposition/orientation of the HMD 510 relative to the reference point onthe console 520. Based on the determined and trackedposition/orientation of the HMD 510, the console 520 may control adirectional beam at the console 520 for wireless communication with theHMD 510. In order to control a directional narrow beam at the HMD 510,the console 520 may transmit a feedback signal with information aboutthe determined and tracked position/orientation of the HMD 510 relativeto the reference point on the console 520. Based on the receivedfeedback signal, the HMD 510 may switch a directional narrow beam forwireless transmission to the console 520. As shown in FIG. 5A, the HMD510 performs wireless communication with the console 520 using adirectional narrow beam 525, and the console 520 performs wirelesscommunication with the HMD 510 using a transmission beam 530 that can beeither a directional wide transmission beam or a directional narrowtransmission beam. In an alternate embodiment (not shown in FIG. 5A),the HMD 510 performs wireless communication with the console 520 using adirectional wide beam.

FIG. 5B is the wireless system 500 where the console 520 applies the“outside-in” positional tracking to switch a beam for wirelesscommunication with the HMD 510 to a preferred direction when the HMD 510moves relative to the console 520, in accordance with an embodiment. Inthe illustrative embodiment shown in FIG. 5B, as the user of the HMD 510moves to the right relative to the console 520, the “outside-in”positional tracking applied at the console 520 may initiate switchingwireless communication with the HMD 510 from the transmission beam 530to a transmission beam 535 to ensure a quality of communication linkbetween the HMD 510 and the console 520 is above a predeterminedthreshold value. Information about the new transmission beam 535 can befed back from the console 520 to the HMD 510 to further fine tune adirectional beam at the HMD 510.

FIG. 5C is the wireless system 500 where the console 520 maintains adirectional beam for wireless communication with the HMD 510 althoughthe HMD 510 changed its position relative to the console 520, inaccordance with an embodiment. In the illustrative embodiment shown inFIG. 5C, as the user of the HMD 510 rotates to the left relative to theconsole 520, a preferred transmission beam at the console 520 (e.g., thetransmission beam 530) may not change. However, the preferredtransmission beam 530 may not be good enough to ensure that a quality ofcommunication link between the HMD 510 and the console 520 is above apredetermined threshold value. Thus, information about a new position ofthe HMD 510 obtained based on the “outside-in” positional trackingapplied at the console 520 needs to be fed back from the console 520 tothe HMD 510 for initiating beam switching at the HMD 510 from adirectional narrow beam 540 to some other directional narrow beam.

In some embodiments, the feedback communicated from the console 520 tothe HMD 510 may increase a latency of beam switching at the HMD 510 incomparison with the “inside-out” positional tracking discussed inconjunction with FIGS. 2A-2C and FIG. 4. However, the latency of the“outside-in” positional tracking applied at the console 520 may stillsupport typical movements of the user of the HMD 510. In an illustrativeembodiment, a total latency of beam switching applied at the HMD 510based on the “outside-in” positional tracking performed at the console520 is a sum of several latencies. A first latency represents a timeperiod for the console 520 to perform tracking of position/orientationof the HMD 510 relative to the console 520, which may take approximately2 ms due to a constellation updating rate of 500 Hz. Following the firstlatency, a second latency represents a software/hardware (SW/HW) timeperiod required for a modem of the console 520 to switch beams at theconsole 520. The SW time period of the console 520 corresponds to a timefor the SW of the console 520 to finish conversion of positionalinformation to a new directional beam; the HW time period of the console520 represents an actual HW switch time and settling time. After that,the positional information of the HMD 510 is fed back from the console520 to the HMD 510 to direct the HMD 510 to switch beam for achievingimproved communication performance. The feedback process and HMD switchbeam operation takes additional HW/SW time period of the HMD 510, whichcorresponds to a third latency. Thus, the total latency of beamswitching based on the “outside-in” positional tracking is equal to thesum of the first latency (e.g., 2 ms), the second latency (e.g., SW/HWtime period of the console 520) and the third latency (e.g., HW/SW timeperiod of the HMD 510). In some embodiments, the latency of beamswitching based on the “outside-in” positional tracking may still belower than a latency of sector level sweep which may be up to 100 ms. Interms of latency, the “outside-in” positional tracking may be lessefficient than the beam refinement protocol. However, the “outside-in”positional tracking may have more reliable accuracy than the beamrefinement protocol.

FIG. 6 is a wireless system that includes a HMD 610 wirelesslycommunicating with a console 620, wherein the console 620 sets up(determines) a radio frequency (RF) zone 625 where a quality of wirelesscommunication between the HMD 610 and the console 620 is above apredetermined threshold level, in accordance with an embodiment. Aquality of wireless link between the HMD 610 and the console 620 outsideof the RF zone 625 is below the threshold value, i.e., the HMD 610cannot reliable operate outside the RF zone 625. The wireless system 600is a wireless VR system, a wireless AR system, a wireless MR system, orsome combination thereof, which can improve RF performance of both theHMD 610 and the console 620. The HMD 610 is an embodiment of the HMD 100shown in FIG. 1A.

In an illustrative embodiment shown in FIG. 6, the HMD 610 performswireless communication with the console 620 using a narrow directionalbeam 630, while the console 620 performs wireless communication with theHMD 610 using a transmission beam 635 within the RF zone 625. In analternate embodiment (not shown in FIG. 6), the HMD 610 may wirelesslycommunicate with the console 620 using a directional wide beam. In anembodiment, the transmission beam 635 of the console 620 is a narrowdirectional beam. In an alternate embodiment, the transmission beam 635is a wide directional beam. In some embodiments, the console 620 appliesthe “outside-in” positional tracking to determine and trackposition/orientation of the HMD 610 relative to a specific referencepoint on the console 620. The console 620 may utilize the determinedposition/orientation of the HMD 610 to switch a transmission beam of theconsole 620, e.g., from the transmission beam 635 to a transmission beam640 or to a transmission beam 645 as a user of the HMD 610 moves withinthe RF zone 625. The console 620 may further transmit a feedback to theHMD 610 with information about the determined position/orientation ofthe HMD 610 relative to the reference point on the console 620. The HMD610 may utilize the received information about the determinedposition/orientation of the HMD 610 relative to the reference point onthe console 620 to switch a transmission beam at the HMD 610 as the userof the HMD 610 moves within the RF zone 625.

In some embodiments, the console 620 transmits a warning message to theHMD 610 indicating that the HMD 610 is approaching an RF deadzone 650outsize the RF zone 625 where a quality of wireless coverage from theconsole 620 is below a predetermined threshold value. In someembodiments, information about the coverage RF zone 625 which is knownat the console 620 may facilitate transmit beam selection at the console620, without an overhead and independently of beam selection at the HMD610. In contrast, in the IEEE 802.11ad standard, in order to traintransmit beam and select a preferred directional beam for wirelesstransmission, feedback is needed about a quality of link associated withthat directional beam. In some embodiments, since the HMD 610 typicallymoves relatively slow in comparison with a time needed for transmissionof a packet between the console 620 and the HMD 610, the console 620 cansend a feedback to the HMD 610 with information about the RF zone 625,so that the HMD 610 can focus a beam tracking only in the RF zone 625instead of performing a complete beam training. This approach savessignificant overhead in the sector level sweep and the beam refinementprotocol procedures.

In some embodiments, a console that wirelessly communicates with a HMDcomprises a module configured for motion prediction. The motionprediction module of the console can predict a “future” position of theHMD relative to a specific reference point on the console, which canfacilitate finding a correct directional beam at the console pointing tothe “future” position of the HMD. Similarly to the “outside-in”positional tracking, the motion prediction applied at the console canonly control a directional beam at the console. In order to control adirectional beam at the HMD, the console may need to transit a feedbackto the HMD with information about the predicted “future” position of theHMD. The motion prediction module included in the console can beconfigured to predict a position/orientation of the HMD for a certainlimited time period in the future, e.g., a time period of 20 ms in thefuture. In one or more embodiments, the motion prediction applied at theconsole can help reduce the number of directional beams that needs to betracked at the console, which reduces beam switching latency at theconsole. In alternate embodiments, motion prediction can be alsoimplemented at the HMD, which can facilitate faster beam switching atthe HMD based on a predicted “future” position of the HMD.

In some embodiments, a HMD that wirelessly communicates with a consoleincludes a DCA, e.g., the DCA 175 shown in FIG. 1B. The DCA may beconfigured to determine depth information of one or more objects in alocal area surrounding some or all of the HMD. In one or moreembodiments, the HMD fuses the determined depth information withpositional information relative to the console (e.g., determined byapplying the “inside-out” positional tracking) to fine tune adirectional beam at the HMD for wireless communication with the console.In one embodiment, the HMD utilizes the depth information to checkwhether a directional beam for communication with the console obtainedbased on the “inside-out” positional tracking is accurate. In alternateembodiments, the HMD uses the determined depth information to obtaininformation about RF deadzone, information about NLOS zone, informationabout LOS blockage, etc. The HMD may use the depth information todetermine whether a user wearing the HMD is approaching a capabilitylimit of the RF system after which a lower performance/throughput isexpected. In yet another embodiment, the determined depth informationcomprises 3D information about objects in the local area as well asinformation about materials of the objects. In this case, the HMD mayutilize the determined depth information to directly calculate beamforming coefficients without using the conventional beam formingalgorithm. The beam forming coefficients calculated in this way may bemore accurate than beam forming coefficients obtained based on theconventional beam forming algorithm. In addition, the depth informationmay be combined with a machine learning process to train the HMD toobtain and predict a beam forming metric.

In some embodiments, a console that wirelessly communicates with a HMDincludes a DCA having the same functionality as the DCA 175 of the HMD100 shown in FIG. 1B. The DCA of the console may be thus configured todetermine depth information of one or more objects in a local areasurrounding some or all of the console. In addition to HMD's positionalinformation (e.g., determined based on the “outside-in” positionaltracking), the console may provide the determined depth information tothe HMD for fine tuning of a directional beam of the HMD for wirelesscommunication with the console.

Disclosed embodiments support a wireless VR, a wireless AR or a wirelessMR system having a console that wirelessly communicates with a HMD. Thejoint cross-layer beam forming methods can be applied that involveRF/PHY/MAC subsystems and the positional tracking subsystems at theconsole and/or the HMD. Directional wide beam(s) can be utilized at theconsole to alleviate beam tracking difficulty. Instead of using standardand traditional mm-wave 60 GHz RF/base-band centric beam tracking, the“inside-out” positional tracking can be implemented at the HMD to assistachieving multi-fold benefits. Other positional tracking methods can bealso applied, such as the “outside-in” positional tracking applied atthe console, at the cost of additional feedback communicated from theconsole to the HMD and the associated longer latency for beam switching.

FIG. 7 is a flow chart illustrating a process 700 of positional trackingassisted beam forming, which may be implemented at the HMD shown in FIG.1A, in accordance with an embodiment. The process 700 of FIG. 7 may beperformed by the components of a HMD (e.g., the HMD 100). Other entitiesmay perform some or all of the steps of the process in otherembodiments. Likewise, embodiments may include different and/oradditional steps, or perform the steps in different orders.

The HMD tracks 710 (e.g., via a positional tracking system) a positionof the HMD. In some embodiments, the HMD tracks the position of the HMDrelative to a reference point on a console that wirelessly communicatingwith the HMD. In some embodiments, the HMD utilizes measurement dataobtained from at least one of a DCA, one or more locators, an IMU andone or more position sensors of the HMD to determine and track theposition of the HMD relative to the reference point on the console.

The HMD generates 720 (e.g., via the positional tracking system)positional information describing the tracked position of the HMD. Forexample, the positional information may comprise information about anangular position of the HMD relative to the reference point on theconsole, information about a rotational position of the HMD relative tothe reference point, information about a 3D coordinate position of theHMD relative to the reference point, etc. In some embodiments, the HMDgenerates 720 the positional information by periodically updatinginformation about the HMD's position relative to the reference point onthe console.

The HMD determines 730 (e.g., via a beam controller) a change in thepositional information. In some embodiments, the HMD determines 730 thatthe change in the positional information is greater than a thresholdvalue, which requires switching to a new directional beam of the HMD forwireless communication with the console. In some embodiments, based onthe tracked positions/orientations of the HMD over a defined timeperiod, the HMD determines 730 the change in the HMD's position relativeto the console. The HMD determines 730 the change in the positionalinformation based on, e.g., comparison between twopositions/orientations that the HMD occupies relative to the console intwo consecutive time instants when the positional information ismeasured.

The HMD determines 740 (e.g., via the beam controller) a directionalbeam, of a plurality of directional beams, based in part on the changeto the positional information. In some embodiments, the directionalbeams are directional narrow beams. In alternate embodiments, thedirectional beams are directional wide beams. In some embodiments, theHMD determines 740 the directional beam based on information about apreviously used directional beam and information about the change toposition/orientation of the HMD relative to a position/orientation ofthe HMD occupied when the previous directional beam was used. As the HMDknows its position relative to the reference point on the console, theHMD selects one directional beam of the plurality of directional beamsof the HMD such that the selected directional beam covers a preferredregion in space that comprises the reference point of the console.

The HMD generates 750 (e.g., via the beam controller) the communicationinstructions identifying the determined beam direction. In someembodiments, the HMD generates 750 the communication instructions thatindicate switching wireless communication with the console to theselected directional beam.

The HMD communicates 760 (e.g., via a transceiver) with the console viaa wireless channel, in accordance with the communication instructions,over the determined directional beam. In some embodiments, the HMDswitches wireless communication with the console to the newly selecteddirectional beam.

FIG. 8 is a flow chart illustrating a process 800 of positional trackingassisted beam forming, which may be implemented at a console wirelesslycommunicating with the HMD shown in FIG. 1A, in accordance with anembodiment. The process 800 of FIG. 8 may be performed by the componentsof a console (e.g., the console 520 in FIGS. 5A-5C and/or the console620 in FIG. 6). Other entities may perform some or all of the steps ofthe process in other embodiments. Likewise, embodiments may includedifferent and/or additional steps, or perform the steps in differentorders.

The console tracks 810 (e.g., via a positional tracking system) aposition of a HMD. In some embodiments, the console tracks the positionof the HMD relative to a reference point on the console. In someembodiments, the console utilizes measurement data obtained from atleast one of a camera, locators, IMU and/or positional sensors fordetermining and tracking the position of the HMD relative to thereference point on the console.

The console generates 820 (e.g., via the positional tracking system)positional information describing the tracked position of the HMD. Forexample, the positional information may comprise information about anangular position of the HMD relative to the reference point on theconsole, information about a rotational position of the HMD relative tothe reference point, information about a 3D coordinate position of theHMD relative to the reference point, etc. In some embodiments, theconsole generates 820 the positional information by periodicallyupdating information about the HMD's position relative to the referencepoint on the console.

The console determines 830 (e.g., via a beam controller) a change in thepositional information. In some embodiments, the console determines 830that the change in the positional information of the HMD is greater thana threshold value, which requires switching to a new directional beam ofthe HMD for wireless communication with the console. In someembodiments, based on the tracked positions/orientations of the HMD overa defined time period, the console determines 830 the change in theHMD's position relative to the console. The console determines 830 thechange in the positional information of the HMD based on, e.g.,comparison between two positions/orientations that the HMD occupiesrelative to the console in two consecutive time instants when thepositional information is measured at the console.

The console determines 840 (e.g., via the beam controller) a directionalbeam of a plurality of directional beams of the HMD, based in part onthe change to the positional information. In some embodiments, thedirectional beams of the HMD are directional narrow beams. In alternateembodiments, the directional beams of the HMD are directional widebeams. In some embodiments, the console determines 840 the directionalbeam based on information about a previously used directional beam atthe HMD and information about the change to position/orientation of theHMD relative to a position/orientation of the HMD occupied when theprevious directional beam was used. As the console knows the HMD'sposition relative to the reference point on the console, the consoleselects one directional beam of the plurality of directional beams ofthe HMD such that the selected directional beam covers a preferredregion in space that comprises the reference point of the console.

The console generates 850 (e.g., via the beam controller) communicationinstructions identifying the determined directional beam. In someembodiments, the console generates 850 the communication instructionsthat indicate switching to the selected directional beam of the HMD forwireless communication with the console.

The console transmits 860 (e.g., via a transceiver) the communicationinstructions to the HMD, the communication instructions causing the HMDto communicate with the console over the determined directional beam. Insome embodiments, the HMD receives the communication instructions andswitches wireless communication with the console to the newly selecteddirectional beam.

System Environment

FIG. 9 is a block diagram of one embodiment of a HMD system 900 in whicha console 910 operates. The HMD system 900 may operate in a VR systemenvironment, an AR system environment, a MR system environment, or somecombination thereof. The HMD system 900 shown by FIG. 9 comprises a HMD905 and an input/output (I/O) interface 915 that is coupled to theconsole 910. While FIG. 9 shows an example HMD system 900 including oneHMD 905 and on I/O interface 915, in other embodiments any number ofthese components may be included in the HMD system 900. For example,there may be multiple HMDs 905 each having an associated I/O interface915, with each HMD 905 and I/O interface 915 communicating with theconsole 910. In alternative configurations, different and/or additionalcomponents may be included in the HMD system 900. Additionally,functionality described in conjunction with one or more of thecomponents shown in FIG. 9 may be distributed among the components in adifferent manner than described in conjunction with FIG. 9 in someembodiments. For example, some or all of the functionality of theconsole 910 is provided by the HMD 905.

The HMD 905 is a head-mounted display that presents content to a usercomprising virtual and/or augmented views of a physical, real-worldenvironment with computer-generated elements (e.g., two-dimensional (2D)or 3D images, 2D or 3D video, sound, etc.). In some embodiments, thepresented content includes audio that is presented via an externaldevice (e.g., speakers and/or headphones) that receives audioinformation from the HMD 905, the console 910, or both, and presentsaudio data based on the audio information. The HMD 905 may comprise oneor more rigid bodies, which may be rigidly or non-rigidly coupledtogether. A rigid coupling between rigid bodies causes the coupled rigidbodies to act as a single rigid entity. In contrast, a non-rigidcoupling between rigid bodies allows the rigid bodies to move relativeto each other. An embodiment of the HMD 905 is the HMD 100 describedabove in conjunction with FIG. 1A.

The HMD 905 includes a DCA 920, an electronic display 925, an opticalassembly 930, one or more locators 935, one or more position sensors940, an IMU 945, a positional tracking system 950, a beam controller955, and a transceiver 960. Some embodiments of the HMD 905 havedifferent components than those described in conjunction with FIG. 9.Additionally, the functionality provided by various components describedin conjunction with FIG. 9 may be differently distributed among thecomponents of the HMD 905 in other embodiments.

The DCA 920 captures data describing depth information of an areasurrounding the HMD 905. The data describing depth information may beassociated with one or a combination of the following techniques used todetermine depth information: structured light, time of flight, or somecombination thereof. The DCA 920 can compute the depth information usingthe data, or the DCA 920 can send this information to another devicesuch as the console 910 that can determine the depth information usingdata from the DCA 920.

The DCA 920 includes an illumination source, an imaging device, and acontroller. The illumination source emits light onto an area surroundingthe HMD 905. The illumination source includes a plurality of emitters ona single substrate. The imaging device captures ambient light and lightfrom one or more emitters of the plurality of emitters of the pluralityof emitters that is reflected from objects in the area. The controllercoordinates how the illumination source emits light and how the imagingdevice captures light. In some embodiments, the controller may alsodetermine depth information associated with the local area using thecaptured images.

The illumination source of the DCA 920 includes a plurality of emittersthat each emits light having certain characteristics (e.g., wavelength,polarization, coherence, temporal behavior, etc.). The characteristicsmay be the same or different between emitters, and the emitters can beoperated simultaneously or individually. In one embodiment, theplurality of emitters could be, e.g., laser diodes (e.g., edgeemitters), inorganic or organic light emitting diodes (LEDs), avertical-cavity surface-emitting laser (VCSEL), or some other source. Insome embodiments, a single emitter or a plurality of emitters in theillumination source can emit light having a structured light pattern.

The DCA 920 may be an embodiment of the DCA 175 in FIG. 1B. The DCA 920may determine depth information of one or more objects in a local areasurrounding some or all of the HMD 905. In one embodiment, the HMD 905may fuse the depth information determined by the DCA 920 with positionalinformation relative to the console (e.g., determined by applying the“inside-out” positional tracking) to fine tune a directional beam at theHMD 905 for wireless communication with the console 910. In anotherembodiment, the HMD 905 uses the depth information determined by the DCA920 to obtain information about RF deadzone, information about NLOSzone, information about LOS blockage, etc. In yet another embodiment,the HMD 905 uses the depth information determined by the DCA 920 todirectly calculate beam forming coefficients without using theconventional beam forming algorithm.

The electronic display 925 displays 2D or 3D images to the user inaccordance with data received from the console 910. In variousembodiments, the electronic display 925 comprises a single electronicdisplay or multiple electronic displays (e.g., a display for each eye ofa user). Examples of the electronic display 925 include: a liquidcrystal display (LCD), an organic light emitting diode (OLED) display,an inorganic light emitting diode (ILED) display, an active-matrixorganic light-emitting diode (AMOLED) display, a transparent organiclight emitting diode (TOLED) display, some other display, a projector,or some combination thereof. The electronic display 925 may also includean aperture, a Fresnel lens, a convex lens, a concave lens, adiffractive element, a waveguide, a filter, a polarizer, a diffuser, afiber taper, a reflective surface, a polarizing reflective surface, orany other suitable optical element that affects the image light emittedfrom the electronic display 925.

The optical assembly 930 magnifies image light received from theelectronic display 925, corrects optical errors associated with theimage light, and presents the corrected image light to a user of the HMD905. The optical assembly 930 includes a plurality of optical elements.Example optical elements included in the optical assembly 930 include:an aperture, a Fresnel lens, a refractive lens, a reflective surface, adiffractive element, a waveguide, a filter, a reflective surface, apolarizing reflective surface, or any other suitable optical elementthat affects image light. Moreover, the optical assembly 930 may includecombinations of different optical elements. In some embodiments, one ormore of the optical elements in the optical assembly 930 may have one ormore coatings, such as partially reflective or anti-reflective coatings,dichroic coatings, etc.

Magnification and focusing of the image light by the optical assembly930 allows the electronic display 925 to be physically smaller, weighless and consume less power than larger displays. Additionally,magnification may increase the field of view of the content presented bythe electronic display 925. For example, the field of view of thedisplayed content is such that the displayed content is presented usingalmost all (e.g., approximately 110 degrees diagonal), and in some casesall, of the user's field of view. Additionally in some embodiments, theamount of magnification may be adjusted by adding or removing opticalelements.

In some embodiments, the optical assembly 930 may be designed to correctone or more types of optical error. Examples of optical error includebarrel or pincushion distortions, longitudinal chromatic aberrations, ortransverse chromatic aberrations. Other types of optical errors mayfurther include spherical aberrations, chromatic aberrations or errorsdue to the lens field curvature, astigmatisms, or any other type ofoptical error. In some embodiments, content provided to the electronicdisplay 925 for display is pre-distorted, and the optical assembly 930corrects the distortion when it receives image light from the electronicdisplay 925 generated based on the content.

The locators 935 are objects located in specific positions on the HMD905 relative to one another and relative to a specific reference pointon the HMD 905. A locator 935 may be a light emitting diode (LED), acorner cube reflector, a reflective marker, a type of light source thatcontrasts with an environment in which the HMD 905 operates, or somecombination thereof. In embodiments where the locators 935 are active(i.e., an LED or other type of light emitting device), the locators 935may emit light in the visible band (˜380 nm to 750 nm), in the infrared(IR) band (˜750 nm to ˜1,800 nm), in the ultraviolet band (˜100 nm to380 nm), some other portion of the electromagnetic spectrum, or somecombination thereof.

In some embodiments, the locators 935 are located beneath an outersurface of the HMD 905, which is transparent to the wavelengths of lightemitted or reflected by the locators 935 or is thin enough to notsubstantially attenuate the wavelengths of light emitted or reflected bythe locators 935. Additionally, in some embodiments, the outer surfaceor other portions of the HMD 905 are opaque in the visible band ofwavelengths of light. Thus, the locators 935 may emit light in the IRband under an outer surface that is transparent in the IR band butopaque in the visible band.

The IMU 945 is an electronic device that generates data indicating aposition of the HMD 905 based on measurement signals received from oneor more of the position sensors 940 and from depth information receivedfrom the DCA 920. A position sensor 940 generates one or moremeasurement signals in response to motion of the HMD 905. Examples ofposition sensors 940 include: one or more accelerometers, one or moregyroscopes, one or more magnetometers, another suitable type of sensorthat detects motion, a type of sensor used for error correction of theIMU 945, or some combination thereof. The position sensors 940 may belocated external to the IMU 945, internal to the IMU 945, or somecombination thereof.

Based on the one or more measurement signals from one or more positionsensors 940, the IMU 945 generates data indicating an estimated currentposition of the HMD 905 relative to an initial position of the HMD 905.For example, the position sensors 940 include multiple accelerometers tomeasure translational motion (forward/back, up/down, left/right) andmultiple gyroscopes to measure rotational motion (e.g., pitch, yaw,roll). In some embodiments, the IMU 945 rapidly samples the measurementsignals and calculates the estimated current position of the HMD 905from the sampled data. For example, the IMU 945 integrates themeasurement signals received from the accelerometers over time toestimate a velocity vector and integrates the velocity vector over timeto determine an estimated current position of a reference point on theHMD 905. Alternatively, the IMU 945 provides the sampled measurementsignals to the console 910, which interprets the data to reduce error.The reference point is a point that may be used to describe the positionof the HMD 905. The reference point may generally be defined as a pointin space or a position related to the HMD's 905 orientation andposition.

The IMU 945 receives one or more parameters from the console 910. Theone or more parameters are used to maintain tracking of the HMD 905.Based on a received parameter, the IMU 945 may adjust one or more IMUparameters (e.g., sample rate). In some embodiments, certain parameterscause the IMU 945 to update an initial position of the reference pointso it corresponds to a next position of the reference point. Updatingthe initial position of the reference point as the next calibratedposition of the reference point helps reduce accumulated errorassociated with the current position estimated the IMU 945. Theaccumulated error, also referred to as drift error, causes the estimatedposition of the reference point to “drift” away from the actual positionof the reference point over time. In some embodiments of the HMD 905,the IMU 945 may be a dedicated hardware component. In other embodiments,the IMU 945 may be a software component implemented in one or moreprocessors.

The positional tracking system 950 uses measurement data obtained fromat least one of the DCA 920, the one or more locators 935, the one ormore position sensors 940, and the IMU 945 to determine and trackposition of the HMD 905 relative to a specific reference point on theconsole 910, i.e., to perform the “inside-out” positional tracking ofthe HMD 905. The positional tracking system 950 further generatespositional information describing the tracked position of the HMD 905.The positional tracking system 950 may generate the positionalinformation by periodically updating information about the position ofthe HMD 905 relative to the reference point on the console 910.

The beam controller 955 determines a change in the positionalinformation determined by the positional tracking system 950. The beamcontroller 955 may obtain from the positional tracking system 950information about positions/orientations of the HMD 905 tracked over adefined time period. Based on the tracked positions/orientations of theHMD 905, the beam controller 955 determines the change in the positionof the HMD 905 relative to the console 910. The beam controller 955determines a directional beam, of a plurality of directional narrowbeams of the HMD 905, based in part on the change to the positionalinformation. As the HMD 905 knows its position relative to the referencepoint on the console 910, the beam controller 955 selects onedirectional narrow beam of the plurality of directional narrow beams ofthe HMD 905 such that the selected directional narrow beam covers apreferred region in space that comprises the reference point of theconsole 910. The beam controller 955 further generates the communicationinstructions identifying the determined directional beam. The beamcontroller 955 generates the communication instructions that indicate tothe transceiver 960 to switch wireless communication with the console910 to the selected directional narrow beam.

The HMD 905 wirelessly communicates, via the transceiver 960, with theconsole 910, in accordance with the communication instructions receivedfrom the beam controller 955, over the determined directional beam.Based on the communication instructions obtained from the beamcontroller 955, the transceiver 960 switches wireless communication withthe console 910 to the newly selected directional narrow beam. Thetransceiver 960 is further configured to receive a feedback signal fromthe console 910, the feedback signal comprising information about aregion where a quality of wireless communication between the HMD 905 andthe console 910 is above a threshold. The beam controller 955 may beconfigured to perform beam tracking based on the information about theregion obtained from the transceiver 960.

The I/O interface 915 is a device that allows a user to send actionrequests and receive responses from the console 910. An action requestis a request to perform a particular action. For example, an actionrequest may be an instruction to start or end capture of image or videodata or an instruction to perform a particular action within anapplication. The I/O interface 915 may include one or more inputdevices. Example input devices include: a keyboard, a mouse, a gamecontroller, or any other suitable device for receiving action requestsand communicating the action requests to the console 910. An actionrequest received by the I/O interface 915 is communicated to the console910, which performs an action corresponding to the action request. Insome embodiments, the I/O interface 915 includes an IMU 945 thatcaptures calibration data indicating an estimated position of the I/Ointerface 915 relative to an initial position of the I/O interface 915.In some embodiments, the I/O interface 915 may provide haptic feedbackto the user in accordance with instructions received from the console910. For example, haptic feedback is provided when an action request isreceived, or the console 910 communicates instructions to the I/Ointerface 915 causing the I/O interface 915 to generate haptic feedbackwhen the console 910 performs an action.

The console 910 provides content to the HMD 905 for processing inaccordance with information received from one or more of: the DCA 920,the HMD 905, and the I/O interface 915. The console 910 communicateswirelessly with the HMD 905. In the example shown in FIG. 9, the console910 includes an application store 965, a tracking module 970, a beamcontroller 975, a transceiver 980, and an engine 985. Some embodimentsof the console 910 have different modules or components than thosedescribed in conjunction with FIG. 9. Similarly, the functions furtherdescribed below may be distributed among components of the console 910in a different manner than described in conjunction with FIG. 9.

The application store 965 stores one or more applications for executionby the console 910. An application is a group of instructions, that whenexecuted by a processor, generates content for presentation to the user.Content generated by an application may be in response to inputsreceived from the user via movement of the HMD 905 or the I/O interface915. Examples of applications include: gaming applications, conferencingapplications, video playback applications, or other suitableapplications.

The tracking module 970 calibrates the HMD system 900 using one or morecalibration parameters and may adjust one or more calibration parametersto reduce error in determination of the position of the HMD 905 or ofthe I/O interface 915. For example, the tracking module 970 communicatesa calibration parameter to the DCA 920 to adjust the focus of the DCA920 to more accurately determine positions of structured light elementscaptured by the DCA 920. Calibration performed by the tracking module970 also accounts for information received from the IMU 945 in the HMD905 and/or an IMU 945 included in the I/O interface 915. Additionally,if tracking of the HMD 905 is lost (e.g., the DCA 920 loses line ofsight of at least a threshold number of structured light elements), thetracking module 970 may re-calibrate some or all of the HMD system 900.

The tracking module 970 tracks movements of the HMD 905 or of the I/Ointerface 915 using information from the DCA 920, the one or morelocators 935, the one or more position sensors 940, the IMU 945 or somecombination thereof. For example, the tracking module 970 determines aposition of a reference point of the HMD 905 in a mapping of a localarea based on information from the HMD 905. The tracking module 970 mayalso determine positions of the reference point of the HMD 905 or areference point of the I/O interface 915 using data indicating aposition of the HMD 905 from the IMU 945 or using data indicating aposition of the I/O interface 915 from an IMU 945 included in the I/Ointerface 915, respectively. Additionally, in some embodiments, thetracking module 970 may use portions of data indicating a position orthe HMD 905 from the IMU 945 as well as representations of the localarea from the DCA 920 to predict a future location of the HMD 905. Thetracking module 970 provides the estimated or predicted future positionof the HMD 905 or the I/O interface 915 to the engine 985. The estimatedposition of the HMD 905 and/or the predicted future position of the HMD905 can be transmitted over a wireless communication link to the HMD905.

The tracking module 970 tracks a position of the HMD 905, e.g., relativeto a reference point on the console 910. The tracking module 970 mayutilize measurement data obtained from various positional sensors of theconsole 910 (not shown in FIG. 9) for determining and tracking theposition of the HMD 905 relative to the reference point on the console910. The tracking module 970 may generate positional informationdescribing the tracked position of the HMD 905. In some embodiments, thetracking module 970 generates the positional information by periodicallyupdating information about the HMD's position relative to the referencepoint on the console 910.

The beam controller 975 determines a change in the positionalinformation obtained from the tracking module 970. Based on the trackedpositions/orientations of the HMD 905 over a defined time period, thebeam controller 975 may determine the change in the HMD's positionrelative to the console 910. The beam controller 975 determines adirectional beam of a plurality of directional narrow beams of the HMD905, based in part on the change to the positional information. As theconsole 910 knows the HMD's position relative to the reference point onthe console 910, the beam controller 975 selects one directional narrowbeam of the plurality of directional narrow beams of the HMD 905 suchthat the selected directional narrow beam covers a preferred region inspace that comprises the reference point of the console 910. The beamcontroller 975 further generates communication instructions identifyingthe determined directional beam. The beam controller 975 generates thecommunication instructions that indicate switching at the HMD 905 to theselected directional narrow beam of the HMD 905 for wirelesscommunication with the console 910. The beam controller 975 of theconsole 910 determines the change in the positional information of theHMD 905, determines the directional beam of the HMD 905, and generatesinstructions for beam switching in lieu of the HMD 905 performing thesefunctions. Based on the change in the positional information, the beamcontroller 975 is also configured to adjust an orientation of a widebeam of the console 910 in cases where the wide beam is not, e.g., anomnidirectional pattern. The beam controller 975 may be furtherconfigured to perform transmit beam selection associated with the HMD905, based on information about a region where a quality ofcommunication between the console 910 and the HMD 905 is above athreshold.

The console 910 wirelessly transmits, via the transceiver 980, thecommunication instructions to the HMD 905. The communicationinstructions received at the HMD 905 cause the HMD 905 to communicatewith the console 910 over the determined directional beam. As the HMD905 receives the communication instructions from the console 910, thetransceiver 960 of the HMD 905 is configured to switch wirelesscommunication with the console 910 to the newly selected directionalnarrow beam. The transceiver 980 transmits content to the HMD 905 usinga directional beam, e.g. a directional narrow beam or a directional widebeam. The transceiver 980 can be also configured to transmit to the HMD905 an indication that the HMD 905 approaches a zone where a quality ofwireless communication between the console 910 and the HMD 905 is belowa threshold, based on the positional information of the HMD 905determined at the console 910. The transceiver 980 is further configuredto transmit a feedback signal to the HMD 905, the feedback signalcomprising information about a region where a quality of wirelesscommunication between the console 910 and the HMD 905 is above athreshold.

The engine 985 generates a 3D mapping of the area surrounding the HMD905 (i.e., the “local area”) based on information received from the HMD905. In some embodiments, the engine 985 determines depth informationfor the 3D mapping of the local area based on information received fromthe DCA 920 that is relevant for techniques used in computing depth. Theengine 985 may calculate depth information using one or more techniquesin computing depth (e.g., structured light, time of flight, or somecombination thereof). In various embodiments, the engine 985 usesdifferent types of information determined by the DCA 920 or acombination of types of information determined by the DCA 920.

The engine 985 also executes applications within the HDM system 900 andreceives position information, acceleration information, velocityinformation, predicted future positions, or some combination thereof, ofthe HMD 905 from the tracking module 970. Based on the receivedinformation, the engine 985 determines content to provide to the HMD 905for presentation to the user. For example, if the received informationindicates that the user has looked to the left, the engine 985 generatescontent for the HMD 905 that mirrors the user's movement in a virtualenvironment or in an environment augmenting the local area withadditional content. Additionally, the engine 985 performs an actionwithin an application executing on the console 910 in response to anaction request received from the I/O interface 915 and provides feedbackto the user that the action was performed. The provided feedback may bevisual or audible feedback via the HMD 905 or haptic feedback via theI/O interface 915.

Additional Configuration Information

The foregoing description of the embodiments of the disclosure has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the disclosure to the precise forms disclosed.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in light of the abovedisclosure.

Some portions of this description describe the embodiments of thedisclosure in terms of algorithms and symbolic representations ofoperations on information. These algorithmic descriptions andrepresentations are commonly used by those skilled in the dataprocessing arts to convey the substance of their work effectively toothers skilled in the art. These operations, while describedfunctionally, computationally, or logically, are understood to beimplemented by computer programs or equivalent electrical circuits,microcode, or the like. Furthermore, it has also proven convenient attimes, to refer to these arrangements of operations as modules, withoutloss of generality. The described operations and their associatedmodules may be embodied in software, firmware, hardware, or anycombinations thereof.

Any of the steps, operations, or processes described herein may beperformed or implemented with one or more hardware or software modules,alone or in combination with other devices. In one embodiment, asoftware module is implemented with a computer program productcomprising a computer-readable medium containing computer program code,which can be executed by a computer processor for performing any or allof the steps, operations, or processes described.

Embodiments of the disclosure may also relate to an apparatus forperforming the operations herein. This apparatus may be speciallyconstructed for the required purposes, and/or it may comprise ageneral-purpose computing device selectively activated or reconfiguredby a computer program stored in the computer. Such a computer programmay be stored in a non-transitory, tangible computer readable storagemedium, or any type of media suitable for storing electronicinstructions, which may be coupled to a computer system bus.Furthermore, any computing systems referred to in the specification mayinclude a single processor or may be architectures employing multipleprocessor designs for increased computing capability.

Embodiments of the disclosure may also relate to a product that isproduced by a computing process described herein. Such a product maycomprise information resulting from a computing process, where theinformation is stored on a non-transitory, tangible computer readablestorage medium and may include any embodiment of a computer programproduct or other data combination described herein.

Finally, the language used in the specification has been principallyselected for readability and instructional purposes, and it may not havebeen selected to delineate or circumscribe the inventive subject matter.It is therefore intended that the scope of the disclosure be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure, which is set forth in the following claims.

What is claimed is:
 1. An apparatus comprising: a positional trackingsystem having built-in sensors, the positional tracking systemconfigured to: track, over a time period using the built-in sensors, aposition of a head-mounted display (HMD) relative to the apparatus thatwirelessly communicates with the HMD, and generate positionalinformation describing the tracked position of the HMD over the timeperiod relative to the apparatus; a beam controller configured to:determine a change in the position of the HMD relative to the apparatusbased on the positional information over the time period, determine adirectional beam of a plurality of directional beams of the HMD, basedin part on the determined change, and generate communicationinstructions identifying the determined directional beam; and atransceiver configured to: communicate directly with the HMD via awireless channel, and transmit the communication instructions to the HMDinstructing the HMD to adjust a direction of wireless communication withthe apparatus to the determined directional beam.
 2. The apparatus ofclaim 1, wherein the transceiver is further configured to communicatedirectly with the HMD using one directional beam of one or moredirectional beams of the apparatus.
 3. The apparatus of claim 1, whereinthe transceiver is further configured to communicate directly with theHMD using one directional beam of one or more directional wide beams ofthe apparatus.
 4. The apparatus of claim 1, wherein: the transceiver isfurther configured to transmit to the HMD an indication that the HMDapproaches a zone where a quality of communication between the apparatusand the HMD is below a threshold, based on the positional information ofthe HMD.
 5. The apparatus of claim 1, wherein: the beam controller isfurther configured to perform transmit beam selection associated withthe apparatus, based on information about a region where a quality ofcommunication between the apparatus and the HMD is above a threshold. 6.The apparatus of claim 1, wherein: the transceiver is further configuredto transmit a feedback signal to the HMD, the feedback signal comprisinginformation about a region where a quality of communication between theapparatus and the HMD is above a threshold.
 7. The apparatus of claim 1,further comprising: a processor configured to predict motion of the HMD,wherein the beam controller is further configured to determine someother directional beam of the plurality of directional beams of the HMD,based on the predicted motion of the HMD, and the transceiver is furtherconfigured to transmit information about the other directional beam tothe HMD, the information causing the HMD to switch communication withthe apparatus to the other directional beam.
 8. A method comprising:tracking, over a time period at an apparatus using built-in sensors ofthe apparatus, a position of a head-mounted display (HMD) relative tothe apparatus that wirelessly communicates with the HMD; generatingpositional information describing the tracked position of the HMD overthe time period relative to the apparatus; determining a change in theposition of the HMD relative to the apparatus based on the positionalinformation over the time period; determining a directional beam of aplurality of directional beams of the HMD, based in part on thedetermined change; generating communication instructions identifying thedetermined directional beam; communicating directly with the HMD via awireless channel; and transmitting the communication instructions to theHMD instructing the HMD to adjust a direction of wireless communicationwith the apparatus to the determined directional beam.
 9. The method ofclaim 8, further comprising: transmitting a feedback signal to the HMD,the feedback signal comprising information about a region where aquality of communication between the apparatus and the HMD is above athreshold.
 10. The method of claim 8, further comprising: predictingmotion of the HMD; determining some other directional beam of theplurality of directional beams of the HMD, based on the predicted motionof the HMD; and transmitting information about the other directionalbeam to the HMD, the information causing the HMD to switch communicationwith the apparatus to the other directional beam.